The Upper Vaitarna lake — which supplies around a fifth of the city’s water — is half a metre from its lowest drawable level, which will run out within a week, reports Sujit Mahamulkar.

The Upper Vaitarna lake — which supplies around a fifth of the city’s water — is half a metre from its lowest drawable level, which will run out within a week.

After that, the Brihanmumbai Municipal Corporation (BMC) will stop accessing the lake, which supplies water to the western suburbs and the island city. “The BMC has never seen the lake go below the lowest drawable level, called dead storage,” said Anand Deodhar, former head of the BMC’s water department.

This will mean the BMC will depend on the city’s remaining four lakes – Modak Sagar, Tansa, Tulsi and Bhatsa – for drinking water for the city. Additional Municipal Commissioner, Anil Diggikar said: “Total water stock in the lakes will last us until July 15.”

The city is currently under a 15 per cent water cut due to the falling lake levels — one of the city’s oldest lakes, Vihar, fell below its lowest drawable level on March 18.

“The BMC currently supplies 2,900 million litres of water per day, but that can’t be sustained up to July 15. Water from dead storage is only for emergencies, so we might have to increase the water cut from 15 to 25 per cent,” said a civic official on condition of anonymity.

The civic body may also draw water from the Upper Vaitarna’s reserve stock.

“We have received permission from the state government to draw water from dead storage. We plan to supply 2,900 MLD to the city up to July 15,” said Vinay Deshpande, head of the civic water department.

The current total stock in the city’s lakes is around 2.84 lakh million litres — last year on the same day, it was 4.67 lakh million litres. Bhatsa, which supplies more than half of our water, has 1.67 million litres — compared to the same time last year when it had 3.09 lakh million litres.

The civic staff is praying that the monsoon arrives in time and it is a good monsoon.

“In case the monsoon delays like last year, then the situation would be out of control. We would have to leave the city for a while,” said a civic official from water department, requesting anonymity.

More than 20 per cent of the city’s water supply is lost to leakage and theft, and 7 to 8 per cent to evaporation.